The goal of our research is to uncover the neuronal mechanisms that limit the development of visual performance in humans and nonhuman primates. We propose experiments to explore the neurobiology of development in functional visual terms. We will study the macaque monkey because its visual system is substantially similar to our own, because its exceptional behavioral abilities permit us to make extensive and detailed behavioral measurements that are impossible in human studies, and because its suitability for biological experiments permits developmental hypotheses about underlying brain functions to be tested directly. 1) We will study the development of mechanisms that analyze global motion signals, both in terms of their perceptual role and in terms of their role in controlling eye movements. We will test the hypothesis that the properties and dynamics of pattern sensitive cells in MT limit global motion perception, while the properties and dynamics of component sensitive cells limit motion-based ocular following. 2) We will study the development of form vision mechanisms at two levels, a middle level represented by the processing of form information defined by texture, and a higher level represented by the perception of Glass patterns, a large family of global form stimuli. We will use developmental data to test the hypothesis that V2 limits the processing of form information. 3) Recent studies of human amblyopes suggest that binocular vision plays a key developmental role in this disorder. We will therefore study the development of binocular function using a motion integration task that requires the brain to combine stationary flickering stimuli delivered to each eye to generate a motion percept. This novel approach to the physiology and development of binocular mechanisms will provide information about the relationship between the development of binocularity and the development of form vision. Our experiments will give unified descriptions of the physiological and behavioral processes whose development supports important components of adult high-level vision. They will provide the foundation for exploring developmental abnormalities that produce the family of visual deficits known as amblyopia. In addition, by studying the development of complex perceptual abilities and of visual cortex beyond V1, they will give new insights into the development of inter- and intra-areal cortical circuits. [unreadable] [unreadable]